FR65814, a novel immunosuppressant isolated from a Penicillium strain. Taxonomy, fermentation, isolation, physico-chemical and biological characteristics and structure assignment.

FR65814, a novel immunosuppressant, was isolated from the cultured broth of Penicillium jensenii F-2883. The structure was assigned to be 5,6-dihydroxy-4-(1,2-epoxy-1,5-dimethyl-4-hexenyl)-1-oxaspiro++ +[2,5]octane by spectroscopic analyses. The compound suppressed the immune response at low concentration. In addition, a structually related component fumagillol, a known carcinolytic agent, was also isolated and found to show immunosuppressive activity.